Process of treating lead and lead alloys



Patented Jan. '12, 1937 PATENT OFFICE rnocnss or rename LEAD AND man ALLOYS George 0. Smith, East Orange, N. 1., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application August 28, 19:0, 7 Serial No. 478,551

25 Claims.

A certain kind oi? commercial pig lead, such as Southeastern Missouri District lead, contains metallic impurities consisting of very smallquantitles of high melting-point metals, such as copper, silver, nickel and cobalt, and has been found to have physical properties which make this kind of lead especially desirable for certain purposes, as for example, for cable sheath alloys. Another kind of commercial pig lead, such as Bunker Hill lead, has a high degree of purity and is particularly characterized bythe almost total absence of theumetals referred to above. This high purity lead has been found not to possess the desirable physical properties to as high a degree as the first mentioned lead. It has furthermore been observed that when lead is alloyed with 1% of antimony, as for use in cable sheaths, the presence of the small quantityof high melting point metals has an addimay be added to lead or to certain lead alloys,

such as antimony lead, at comparatively low temperatures and inexact, small quantities to produce lead alloys with improved physical properties.

During an extensive investigation of lead and lead antimony alloys it was found that comparatively small quantities of oxides and certain salts, such as chlorides, of these high melting point metals are practically completely reduced in the presence of the lead or antimonyunder the application of heat, that is, the free metal present replaces and liberates the one contained in the salt or the oxide, 'at least in. those instances where the heat of formationof the new salt 'or oxide is higher than'that of the original salt or oxide. Certain other salts of these metals,

such, as bromides, fluorides, and iodides react similarly to the chlorides.

Thus, when small quantities of chlorides of high melting-point metals, such as copper, silver, nickel, cobalt and others, are added to a large 5 bath of molten lead, the lead replaces all of the high melting-point metal of the salt to form lead chloride and theliberated high meltingpoint metal then alloys with the lead. Therequired temperaturefor the reaction need only be slightly above the melting point of lead chloride. Similar reactions take place when, the chlorides are added either to a bath of molten antimony or to a bath of molten lead antimony" I alloy; 16

Certain oxides, which do not readily react with lead in a process such as that described, have been found to reactwith antimony in such a process. When copper oxide is in contact with molten lead at a temperature of approximately go 500 C. metallic copper and lead oxide are formed and, when there is an excess of lead, an alloy of lead and copper results. Oxides of copper, cobalt, nickel and iron react similarly with molten'antimony resulting in alloys which'mayxbe used as addition products in the manufacture I of lead antimony alloys containing these metals;

or'the oxides can be brought into contact with a lead antimony alloy whereupon, at a temperature of approximately500 C.,'the antimony in the'alloywill reduce the oxides and the copper, cobalt, nickel and iron will enter the melt. The by-products of the reaction is antimony oxide.

An important feature of the method resides in the fact that practically the total amount of as metal added in the form of salt or oxide enters into the lead.

Another important feature resides in the fact that the process may be carried out at temperatures considerably below the melting points of 40 the metal to be added, the highest necessary temperature used in the process being not much above the melting point of lead. This fact is of advantage in a commercial process in that the process is simplified thereby and is made more economical.

A further advantage observed in connection with the use of chlorides is due to the mum lead chloride formed during the reaction is not w miscible with lead and therefore readily separates from the lead product without contaminating it. Thelead chloride formed floats on the molten metal and serves as a flux. Certain other canpounds oflead, such as-lead-phosphide and lead It sulphide do not possess the property of not conplace in the mold by maintaining a sumcient taminating the final product.

It is well known in the art to reduce metallic salts or oxides in the presence of other metals, but the prior methods have 'either been in the nature of laboratoryexperiments, or thealloying constituents or thetemperatures have been difierent from those used in the present process as defined by the appended claims.

In practicing the process in accordance with the invention, silver, copper, nickel and cobalt i have been alloyed with lead by adding the chloride of these metals. Antimony has also been alloyed with silver, copper, nickel and cobalt by the addition of the chlorides of these metals. Copper has been added to lead as well as to antimony by adding copper oxide tothe metallic lead and antimony. The percentage of high melting point metal that may be added by thisprocess is difierent for the different metals and varies from less than .5% to a few percent of the lead or antimony. I

In preparing these alloys one procedure .was to melt pure lead and heat to 525 C. in a crucible, remove the crucible from the furnace and skim the dross of! thesurface of the melt; the chlorides or oxides of the metals to be incor porated were then added; themolten metal was stirred and when its temperature was about 410 C. the dross was removed again and the alloy was castinto molds. Another procedure, which has been used successfully, involved theaddition of 1% orslightly more of'antimony to'the molten lead; the process was then continued as just described. In.

thisprocedure ant mO chloride will be formed during, the reaction instead of lead chloride, for,

whichreason a loss of antimony must be antici pated.

Stillanother-procedure, which has been used successfully involves the addition of one percent or moreof antimony, either as metallic antimony or as an addition alloy of lead and antimony,.tothe molten lead immediately after the small quantities of the other metals have been incorporated.

- In some cases antimony was used instead of lead for alloying with the highfmelting-point metal, the procedure being substantially the same as when lead was used and the resultingalloy was in turn added to lead. It should be understood that other metals than those described may be. added to lead or antimony by this process; for example, arsenic, lead, bismuth, and iron may be added to anti-i mony by means of their chlorides; arsenic may be added to lead by means of its chloride; and

arsenic; bismuth, cobalt, iron, lead and nickelv maybe added to. antimony vby means of their,

- also possible to add the ingredients to the lead or the antimony at ordinary room temperature and then heat to'about 500 C. It is also within the scope of the invention toadd the chlorides of the desired metals to the lead in the mold, by, for example first placing the chlorides in the mold -and then pouring the lead or lead alloy into the mold, permitting the reaction to take the chloride of which has a-heat of formation less than that of lead chloride in an amount less than 5% by weight of the lead which comprises reducing a quantity of chloride of said metal in a bath of said lead, free of alkaline metals, at a temperature between the melting point of said lead and 600 C., said quantity of chloride of said metal containing the approximate desired amount of said metal to be added.

2. A method of alloying a definite small quantityof copper with lead, which comprises adding together in a container lead, antimony and chloride of copper, both said lead and said antimony being free of alkaline metals, and maintaining the temperature of the contents of. said container at about 400 to 500 C. for at least a .few minutes.

3. A method of alloying cobalt with lead in t a desired amountof not more than .4% of the lead which comprisesmaintaining. a bath of molten lead, which is freeof alkaline metals at a temperature not more than about 100 C.

above the melting-point of lead chloride, and addingthe amount of cobalt in'the form oi.

cobalt -chloride to the bath.

4. A method of alloying 'copner with lead a desired amount of not more than.1%, of the lead'which comprises maintaining. a bath of molten lead, free of alkaline 'metals,fat a temperature not more than; about 100 C. abovev the melting pointv of lead chloride and adding the amount of copper in theiorm of copper chloride to the bath. 1

' s. A 'method of alloying silver with lead in a, desired amount of not more than 1% of the lead, which comprises adding v together lead,

of silver in the form of silver chloride and mainwhich is free of alkaline metals, and the amount 5' lead chloride fora few minutes after'said adding.

6. A method of alloying silver and, copperw'ith lead in desired amountseachof not more than 1% of the lead which comprises adding together lead, free of alkaline metals, and the amounts of silver and copper in the form of chlorides and maintaining the lead at'a temperature not more than about 100 C. above the melting point of lead chloride for a few minutes after said adding.

' '7. A method of alloyingwith lead in a desired amount of not more than 1% of the lead which comprises maintaininga bath of molten lead,

free of alkaline metals, at a temperature not more than about 100 C. above the melting point of lead halide and adding the amount of copper in the form of a halide to the bath. p

8. A method of improving the physical proper ties of lead by the addition thereto of a small quantity of a metal having a higher melting point than that of lead, said method 'comprising'adding to the lead, which is free of alkaline metals,

a quantity of a compound comprising said metal a and anon-metallic constituent selected from the group which consists of oxygen, fluorine, chlorine, bromine and iodine, said compound having a I lower heat of formation than the compound comprisinglead and said non-metallic constituent, said last mentioned compound being not readily miscible with said lead and said lead being maintained at aitemperature between the melting point of said lead and the boiling point .of the compound comprising lead and said non-metallic constituent.

9.,A method of improving the physical-properties of. alloys comprising chieiiylead by the "addition thereto of small quantities of metal having a higher, melting point than that of the alloy, said method comprising'adding to the alloy, which is free of alkaline metals, a desired quantity of the halide of said metal at a term perature between the melting point of said alloy and the boiling point of the corresponding halide of lead, said halidecf said metalhaving a lower heat of formation'thansaid corresponding halide of lead and said halide oflead being not readily miscible with said alloy.

10. A method of improving the physical prop- I erties of lead alloy by the addition thereto of small quantities of a metal having a higher melting point than that of the alloy, said method comprising adding to the alloy, which is free of alkaline metals, a desired quantity of the halide of said metal, said halide having a lower heat of formation than the corresponding halide of lead, said halide of lead not being readily miscible with said alloy, and heating said mixture to a temperature approximately between the melting point of said lead halide and 100 C. higher.

. 11. The method of forming an alloy comprising a copper and lead which comprises subjecting a molten bath maintained at a temperature be- 7 low. the boiling point of lead chloride and containing metallic lead, which is free of alkaline metals, to the action of a chloride of copper thereby to efi'ect the precipitation and dispersion of metallic copper in the molten bath.

12. A method of incorporating a metal having a higher melting point than that of lead in an alloy comprising metallic lead, said method comprising subjecting a molten bath of said alloy to the action of a compound comprising said metal and a non-metallic constituent selected from the group which consists of oxygen, fluorine, chlorine, bromine and iodine, said compound having a lower heat of formation than the compound comprising lead and said non-metallic constituent, said compound comprising said metal reacting with said metallic lead to disperse said metal in said alloy and to form a compound comprising lead and said non-metallic constituent which is substantially non-miscible in said alloy in the absence of sumcient alkaline metals in said bath to introduce the desired'amount of said high melting point metal by the interaction of said alkaline metals with said compound comprising said high melting point metal, at a temperature below the boiling point of said compound comprising lead. M

13. The method of forming an alloy comprising copper and lead which comprises subjecting a molten bath comprising metallic lead to the action of a compound comprising copper and a non-metallic constituent, said compound having a lowerlieat of formation than the compound comprising lead and said non-metallic constituent, said compound comprising copper reacting with said metallic lead to form metallic copper and a compound comprising lead and said non-metallic constituent which does not contaminate the resulting alloy in the absence of suflicient alkaline metals in said bath' to introduce the desired amount of copper by the interaction of said alkaline metals with said copper compound, said bath being maintained at a temperature below the boiling point of said compound comprising lead and said non-metallic constituent.

14. The method of forming an alloy comprising copper and lead which comprises subjecting a molten bathof metallic lead, which is free "of alkaline metals, to the action of an amount of copper chloride equivalent to about 1.2 pounds of copper per ton of lead in the bath said bath being maintained at a temperature below the boiling point of lead chloride.

15. A method of alloying copperwith lead comprising: subjecting'a chloride of copper to a molten bath of an alloy comprising lead and a m'etalother than a member of the alkaline group which reacts with the chloride of copper to form metallic copper and the chloride of said metal. said bath being maintained at a temperature below the boiling point of lead chloride.

16. A method of forminga lead alloy comprising subjecting an alloy consisting of lead and elements having a higher melting point than that of lead to the action of a compound comprising a metal having a higher melting point than that of lead and a non-metallic constituent selected from the group which consists of fluorine,

, chlorine, bromine and iodine and oxygen at a- .comprising lead and said non-metallic constituent, said compound of said metal having a lower heat of formation than the corresponding compound of lead.

1'7. A method of incorporating metals having a higher melting point than that of lead in lead, said method comprising subjecting an alloy consisting of lead and elements having a higher melting point than that of lead to the action of the halide of a metal having a higher melting point than that of lead at a temperature between the melting point of said alloy and the boiling point of lead halide, the halide of said metal having a lower heat of formation than the corresponding halide of lead.

18. A method of incorporating copper in lead comprising subjecting a molten bath of an alloy consisting of lead and elements having a higher melting point than that of lead maintained at a temperature below the boiling point of lead halide to the action of a halide of copper whereby copper is dispersed throughout said alloy.

19. A method of incorporating a metal having a higher melting point than thatof lead in an alloy comprising metallic lead, said method comprising subjecting a molten bath of said alloy to the action of a halideof said metal in the absence of sufficient alkaline metals in said bath to introduce the desired amount of said high melting point metal by the interaction of said alkaline metals with said halide, said halide having a lower heat of formation than the corresponding lead halide at a temperature below the antimony and silver chloride, both said lead and said antimony being free or alkaline metals, and maintaining the temperature of the contents of said container-at about 400 to 500 C. r

'22. The method of forming an alloy comprising cobalt and lead which comprises subjecting I a molten bath maintained at a temperature below the boiling point of, lead chloride and containing lead which is free of alkaline metals to the action a or a chloride of cobalt thereby to effect the precipitation-and dispersion of metallic cobalt in the molten bath. a

2 3. The method of forming lament-mas,

ing silver and lead which comprises subjecting a molten nbath maintained at a'temperature below the boiling point of I lead chloride and containing metallic lead which is free of alkaline metal to 1 themaction of silver chloride thereby toeflect the precipitation and. dispersion of metallic silver in the molten bath. a

24; A method 0! incorporating cobalt inlead comprising subjecting a molten bath of an alloy, consistingof leadandelementsl having a higher melting'point than-that of lead and maintained at a temperature below'the boiling point of lead halide to the action of a halide of cobalt whereby cobalt is dispersed throughoutsaid alloy;

25. A method incorporating silver in lead com- I prising subjecting a molteribathof an alloy consisting of lead andelements' having a higher melting point than thatof lead andmaintained at atemperature below the boiling, point of lead halide to the action of a halide of silver whereby silver is dispersed throughout said alloy. f

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